In its efforts to economize in container manufacture while yet seeking to meet the demand of drop tests and like performance standards and to lessen container static weight and hence transportation costs, the container industry has looked extensively to the use of non-metals. In industrial shipping containers, efforts to eliminate or lessen metal usage have taken widely diverse directions. In Carpenter U.S. Pat. No. 3,357,626 a drum is disclosed having body or shell formed by winding laminated layers of fiberboard into an open-ended cylinder which is then sealed. With the shell placed in a press, a plastic parison is extruded inside the shell and beyond the ends thereof. Upon closure of the press, bottom and top portions of the parison are closed and the parison is blown to conform to the form defined by the shell and the bottom and top die faces of the press. End covers are secured to the lined fibrous shell by use of metal reinforcing chimes. Other forms of such plasticlined fibrous shell containers made in similar manner are shown in Carpenter U.S. Pat. Nos. 3,445,049 and 3,266,390 and in Heisler et al. U.S. Pat. No. 3,262,628.
In Moore U.S. Pat. No. 2,823,826 a drum shell is formed of plural wall sections of fiberglass composition. Adjacent wall sections include interleaved margin portions which are interlocked by a common pin member. The shell interior is lined with impervious material to render it leakproof.
A further drum, in present commercial use and known as the "Greif Plastic Drum", produced by Grief Bros. Corporation, is comprised of a plastic body or shell with plastic closure members secured to the ends of the shell, however, by steel reinforcing chimes which encircle the shell ends and are crimped over the closure members. The top closure member has a dome-shaped central part continuous with a peripheral part which is engaged circumferentially by the upper reinforcing chime with spaced radially extending ribs connecting the central and peripheral parts to provide added strength for stacking and holding contents.
In making containers of exclusive plastic composition, various blow molding practices are known wherein an extruded parison is blown to conform to a mold cavity to provide a one-piece container. Unitarily molded shells with integral or detachable bottom and/or top closure members are disclosed in various U.S. patents including Reynolds U.S. Pat. No. 3,827,595, Ainslee U.S. Pat. No. 3,370,737, Sears, Jr. et al. U.S. Pat. No. 3,357,593, Somme U.S. Pat. No. 3,115,281, Hoeffelman U.S. Pat. No. 3,424,343, Rowe U.S. Pat. No. 3,826,404, Uemura U.S. Pat. No. 3,405,439 and Nughes U.S. Pat. No. 3,524,568. Whiteford U.S. Pat. No. 3,184,524 discloses a further alternative wherein a preform is peripherally clamped and centrally pressed into desired form defined by a mold.
The manufacture of plastic containers by processing molding material within forming dies has the evident disadvantage of rendering the production of different-sized containers quite costly. Thus, molds of diverse length and volume are required for making each uniquely sized container. Waste also occurs since container thickness is not uniformly maintainable in molding practices, i.e., containers are unnecessarily thick-walled in corner and like areas. Manufacture of containers by other obove-discussed techniques is complicated by the need for forming fibrous shells by winding and sealing laminates or joining sections and then applying a sealing lining thereto. Regarding the reference commercially-available drum, the same is a metal-reinforced plastic drum and its manufacture further entails the need for reinforcing its closure member by radial ribs as above considered.